1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device where a contact hole is perforated in an insulating layer formed on a refractory metal layer.
2. Description of the Related Art
In a prior art method for manufacturing a semiconductor device, an insulating layer is formed on a refractory metal layer, and a contact hole is perforated in the insulating layer by a dry etching process using CF.sub.4 gas. This will be explained later in detail.
In the prior art method, however, the etching rate ratio of the insulating layer to the refractory metal layer by the dry etching process using CF.sub.4 gas is not sufficiently large. Therefore, the refractory metal layer is overetched. As a result, an electrode or a connection layer deposited on the refractory metal layer is easily separated therefrom, which increases a contact resistance therebetween.
In addition, if the power of the dry etching process is increased to increase the above-mentioned etching ratio, the throughput is decreased.
On the other hand, assume that an insulating layer is formed on active regions of a semiconductor substrate. In this case, when the insulating layer is overetched, the active regions of the semiconductor substrate are exposed to CF.sub.3.sup.+ ions which causes damage thereof.